Area Forecast Discussion
Issued by NWS State College, PA
Issued by NWS State College, PA
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365 FXUS61 KCTP 112120 AFDCTP Area Forecast Discussion National Weather Service State College PA 520 PM EDT Tue Jun 11 2024 .SYNOPSIS... A pocket of cool air in the mid levels of the atmosphere will help to create plenty of clouds today with afternoon high temperatures averaging 5 to 10 degrees below normal for the date. High pressure will build over Pennsylvania late today through Wednesday. As the high drifts east of the region, heat and humidity will ramp up for Thursday and Friday, followed by a cold frontal passage with scattered thunderstorms during the day Friday. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Anomalously cold air in the 850-700 mb layer and shallow moisture advecting SE from the Lower Glakes will help to maintain plenty of clouds across the Northern and Western portions of the CWA today. The clouds are generally stratocu with bases 2500-3500 ft AGL. Vertical mixing of dry air above the cloud deck near and to the SE of the Allegheny Front will create some significant holes in the mid-late afternoon, while bkn-ovc skies could persist for much or all of the day near, and just to the east of the RT 219 corridor from the Laurel Highlands to the NW Mtns of PA. High temps will be in the mid 60s - mid 70s today, once again 5-10 deg below climo. High pressure will begin to build in Tonight, which will bring clearing skies and light/variable wind under 4 kts. Patchy, or even some larger areas of fog are possible across primarily the Northern Mtns of PA, with overnight lows ranging from the upper 40s northwest to mid 50s southeast. Air/water delta Ts should be around 20 deg F. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY NIGHT/... Wednesday will be a transition day between much below normal temps to start the week and warmer weather for Thursday and Friday. Variable amounts of mid and high clouds on Wed will have only a minimal impact on the otherwise abundant sunshine with highs ranging from the low to mid 70s over the Northern Mtns to the low 80s throughout the Valleys of Central and southern PA. These readings will be just a few deg F shy of climo. Winds will be light from the west. PWAT values will start out around 0.8 inch and will increase to around 1 inch Wed afternoon, but it won`t feel humid given sfc dewpoints remaining in the 40s and 50s. We`re still expecting a warm up for the second half of the week, with many locations seeing their warmest temps on Thursday, except perhaps southeast PA seeing temps a few degrees warmer on Fri. Temperatures on Friday will depend on the timing of clouds and convection associated with an approaching cold front. Over the past 24 hours, models have generally sped up the arrival time and southward progression of the aforementioned front, now bringing a chance of showers and thunderstorms to the northern Alleghenies as early as Thursday night, and then dropping south across central PA during the day Fri with more numerous showers and thunderstorms. Despite forecast high temps near 90 across southern zones Thu- Fri, relatively low levels of humidity (dewpoints 55-65F) will hold the heat index to just a couple deg above the air temp. Thus not anticipating heat products at this time. However, the +15-20 degree swing from temps well below normal early this week to the warm weather late this week will be noteworthy. && .LONG TERM /SATURDAY THROUGH TUESDAY/... Next weekend looks dry, as a northerly flow of drier air from Canada is advected into our area. Plenty of sunshine and fair weather is expected for Saturday and Sunday. Any slight cool down on Saturday will be short- lived, with warmer temperatures progged to build back into the area Sunday into Monday. A few isolated sprinkles could be possible in the northern tier of PA with weak diurnally driven updrafts on Monday afternoon. The risk for excessive heat will increase into the middle of the upcoming week as a large ridge builds over the eastern US. && .AVIATION /21Z TUESDAY THROUGH SUNDAY/... Late afternoon update. Clouds holding on late this afternoon. A few minor adjustments. Earlier discussion below. As of 18z Tue, a BKN-OVC stratocu deck was observed across much of Pennsylvania, with notable clearing over the southwest corner of PA in the past 2 hours. Cloud bases are generally in the 2500-3500 ft range, but as low as 1500 ft in the northern tier. Gradual improvement is expected through the late afternoon and evening hours, with BFD likely the last TAF site to trend to VFR this evening. The forecast is more uncertain tonight. We expect most locations to remain VFR, but there will be some valley fog that develops, especially in the vicinity of deep river valleys and where the skies are clear for longest. Some hires guidance also suggests more widespread IFR or LIFR cigs developing in the northern Alleghenies into the Endless Mountains, building back on to whatever cloud mass remains from this afternoon. All TAF sites should trend to VFR by mid morning on Wed, with mid-high altocu or cirrus and a light westerly breeze. Outlook... Thu...Predominantly VFR w/ no sig wx expected. Fri...Restrictions possible in CB/TSRA. Sat-Sun...Predominantly VFR. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Lambert NEAR TERM...Lambert/Colbert SHORT TERM...Lambert/Colbert LONG TERM...Evanego/Bowen AVIATION...Jurewicz/Martin/Colbert